The invention relates to material removing machines, such as mining machines, and more particularly to improvements in devices for mounting or holding material removing tools (e.g., bits) in such machines.
Commonly owned German Utility Model No. G 88 05 961.8 discloses a tool mounting device having a base which is affixed to the mining machine and a tool holder which is separably interfitted with the base. The base has a tapped polygonal nut which extends into a complementary recess of the tool holder, and the latter has an opening for the shank of a screw which is driven into the nut to affix the tool holder to the base. The tool holder is provided with a collar which surrounds a through hole or bore for the shank of the material removing tool and is receivable in a recess of the base. The shank of the material removing tool is mounted only in the tool holder.
U.S. Pat. No. 3,865,437 to Crosby discloses a rotary mining tool retaining structure wherein the shank of the bit is elastic and must be deformed preparatory to insertion into the socket (namely a through bore or hole) of a tool holder. Alternatively, the pronged shank of the tool is receivable in a sleeve which, in turn has a pronged shank receivable in a through hole or bore of the tool holder.
A drawback of a pronged shank, particularly on a material removing tool for use in a mining or like machine, is that the tool is likely to become separated from its holder when the machine employing the tool is in actual use. Moreover, the tool holder of Crosby can accept only specially designed tools, namely tools with slotted shanks which can be deformed for introduction into the socket of the tool holder or into the socket of the aforementioned sleeve.
Certain other types of holders for bits and analogous material removing tools for use in mining and like machines are disclosed in commonly owned U.S. Pat. No. 4,744,605 granted May 17, 1988.